Sharded pubsub command execution within multi/exec (valkey-io#13)

Allow SPUBLISH command within multi/exec on replica.

Author: hpatro

src/cluster.c

@@ -1030,9 +1030,11 @@ clusterNode *getNodeByQuery(client *c, struct redisCommand *cmd, robj **argv, in
         mc.cmd = cmd;
     }
 
-    int is_pubsubshard = cmd->proc == ssubscribeCommand ||
-                         cmd->proc == sunsubscribeCommand ||
-                         cmd->proc == spublishCommand;
+    uint64_t cmd_flags = getCommandFlags(c);
+    
+    /* Only valid for sharded pubsub as regular pubsub can operate on any node and bypasses this layer. */
+    int pubsubshard_included = (cmd_flags & CMD_PUBSUB) ||
+                           (c->cmd->proc == execCommand && (c->mstate.cmd_flags & CMD_PUBSUB));
 
     /* Check that all the keys are in the same hash slot, and obtain this
      * slot and the node associated. */
@@ -1109,7 +1111,7 @@ clusterNode *getNodeByQuery(client *c, struct redisCommand *cmd, robj **argv, in
              * node until the migration completes with CLUSTER SETSLOT <slot>
              * NODE <node-id>. */
             int flags = LOOKUP_NOTOUCH | LOOKUP_NOSTATS | LOOKUP_NONOTIFY | LOOKUP_NOEXPIRE;
-            if ((migrating_slot || importing_slot) && !is_pubsubshard)
+            if ((migrating_slot || importing_slot) && !pubsubshard_included)
             {
                 if (lookupKeyReadWithFlags(&server.db[0], thiskey, flags) == NULL) missing_keys++;
                 else existing_keys++;
@@ -1122,11 +1124,10 @@ clusterNode *getNodeByQuery(client *c, struct redisCommand *cmd, robj **argv, in
      * without redirections or errors in all the cases. */
     if (n == NULL) return myself;
 
-    uint64_t cmd_flags = getCommandFlags(c);
     /* Cluster is globally down but we got keys? We only serve the request
      * if it is a read command and when allow_reads_when_down is enabled. */
     if (!isClusterHealthy()) {
-        if (is_pubsubshard) {
+        if (pubsubshard_included) {
             if (!server.cluster_allow_pubsubshard_when_down) {
                 if (error_code) *error_code = CLUSTER_REDIR_DOWN_STATE;
                 return NULL;
@@ -1189,7 +1190,7 @@ clusterNode *getNodeByQuery(client *c, struct redisCommand *cmd, robj **argv, in
      * is serving, we can reply without redirection. */
     int is_write_command = (cmd_flags & CMD_WRITE) ||
                            (c->cmd->proc == execCommand && (c->mstate.cmd_flags & CMD_WRITE));
-    if (((c->flags & CLIENT_READONLY) || is_pubsubshard) &&
+    if (((c->flags & CLIENT_READONLY) || pubsubshard_included) &&
         !is_write_command &&
         clusterNodeIsSlave(myself) &&
         clusterNodeGetSlaveof(myself) == n)

tests/unit/cluster/sharded-pubsub.tcl

@@ -0,0 +1,56 @@
+start_cluster 1 1 {tags {external:skip cluster}} {
+    set primary_id 0
+    set replica1_id 1
+
+    set primary [Rn $primary_id]
+    set replica [Rn $replica1_id]
+
+    test "Sharded pubsub publish behavior within multi/exec" {
+        foreach {node} {primary replica} {
+            set node [set $node]
+            $node MULTI
+            $node SPUBLISH ch1 "hello"
+            $node EXEC
+        }
+    }
+
+    test "Sharded pubsub within multi/exec with cross slot operation" {
+        $primary MULTI
+        $primary SPUBLISH ch1 "hello"
+        $primary GET foo
+        catch {[$primary EXEC]} err
+        assert_match {CROSSSLOT*} $err
+    }
+
+    test "Sharded pubsub publish behavior within multi/exec with read operation on primary" {
+        $primary MULTI
+        $primary SPUBLISH foo "hello"
+        $primary GET foo
+        $primary EXEC
+    } {0 {}}
+
+    test "Sharded pubsub publish behavior within multi/exec with read operation on replica" {
+        $replica MULTI
+        $replica SPUBLISH foo "hello"
+        catch {[$replica GET foo]} err
+        assert_match {MOVED*} $err
+        catch {[$replica EXEC]} err
+        assert_match {EXECABORT*} $err
+    }
+
+    test "Sharded pubsub publish behavior within multi/exec with write operation on primary" {
+        $primary MULTI
+        $primary SPUBLISH foo "hello"
+        $primary SET foo bar
+        $primary EXEC
+    } {0 OK}
+
+    test "Sharded pubsub publish behavior within multi/exec with write operation on replica" {
+        $replica MULTI
+        $replica SPUBLISH foo "hello"
+        catch {[$replica SET foo bar]} err
+        assert_match {MOVED*} $err
+        catch {[$replica EXEC]} err
+        assert_match {EXECABORT*} $err
+    }
+}